cxx-qt-gen: use impl cxx_qt::QObject<T> block for invokables

This helps later as the invokables are implemented onto a different
struct, so this clearly defines the split between C++ and Rust
methods etc.

README.md

@@ -88,7 +88,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn increment(&self, cpp: &mut CppObj) {
             cpp.set_number(cpp.number() + 1);

book/src/qobject/rustobj_struct.md

@@ -20,12 +20,17 @@ The RustObj struct allows you to define the following items
 
 ## Invokables
 
-To define a method which is exposed to QML and C++, add a method on the `RustObj` struct and add the attribute `#[invokable]`. The parameters and return type are then matched to the Qt side. Also CXX-Qt automatically adds wrapper code around your invokable to automatically perform any conversion between the [C++ and Rust types](../concepts/types.md).
+A `impl cxx_qt::QObject<RustObj>` is used to define invokables, the `impl cxx_qt::QObject<RustObj>` defines that the methods are implemented onto the C++ QObject.
+Therefore they have access to both C++ and Rust methods. Also CXX-Qt adds wrapper code to around your invokables to automatically perform any conversion between the [C++ and Rust types](../concepts/types.md).
+
+To mark a method as invokable simply add the `#[invokable]` attribute to the Rust method. This then causes `Q_INVOKABLE` to be set on the C++ definition of the method, allowing QML to call the invokable.
 
 Note to access properties on the C++ object use [Cpp Object](./cpp_object.md).
 
 ## Private Methods and Fields
 
 Unlike the [Data Struct](./data_struct.md) fields which are defined on the `RustObj` struct are not exposed as properties to Qt. These can be considered as "private to Rust" fields, and are useful for storing channels for threading or internal information for the QObject.
 
-Methods implemented on the `RustObj` that do not have an `#[invokable]` attribute are not exposed to C++ and are considered "private to Rust" methods. Similar to fields these are useful for threading and internal information.
+Methods implemented using `impl RustObj` (and not `impl cxx_qt::QObject<RustObj>`) are just normal Rust member methods.
+Therefore they do not have access to any C++ or QObject functionality (e.g. emitting Signals, changing properties, etc.)
+You will usually only need to use `impl RustObj` if you want to also use your RustObj struct as a normal Rust struct, that is not wrapped in a QObject.

cxx-qt-gen/src/extract.rs

@@ -171,8 +171,10 @@ pub struct QObject {
     pub ident: Ident,
     /// All the methods that can also be invoked from QML
     pub(crate) invokables: Vec<Invokable>,
-    /// All the methods that cannot be invoked from QML
+    /// All the methods that cannot be invoked from QML (but are on the C++ object)
     pub(crate) normal_methods: Vec<ImplItemMethod>,
+    /// All the rust only methods
+    pub(crate) rust_methods: Vec<ImplItem>,
     /// All the properties that can be used from QML
     pub(crate) properties: Vec<Property>,
     /// All the signals that can be emitted/connected from QML
@@ -466,7 +468,7 @@ fn extract_invokables(
             .cloned()
             .collect();
 
-        // Skip non-invokable members
+        // Non invokable methods we just pass through as normal methods
         if filtered_attrs.len() == method.attrs.len() {
             normal_methods.push(method);
             continue;
@@ -847,6 +849,8 @@ pub fn extract_qobject(
     let mut object_invokables = vec![];
     // A list of the normal methods (i.e. not invokables) for the struct
     let mut object_normal_methods = vec![];
+    // A list of the rust only methods for the struct
+    let mut object_rust_methods = vec![];
     // A list of original trait impls for the struct (eg `impl Default for Struct`)
     let mut original_trait_impls = vec![];
     // A list of insignificant declarations for the mod that will be directly passed through (eg `use crate::thing`)
@@ -943,7 +947,7 @@ pub fn extract_qobject(
                 // Extract the path from the type (this leads to the struct name)
                 if let Type::Path(TypePath { path, .. }) = &mut *original_impl.self_ty {
                     // Check that the path contains segments
-                    if path.segments.len() != 1 {
+                    if path.segments.is_empty() {
                         return Err(Error::new(
                             original_impl.span(),
                             "Invalid path on impl block.",
@@ -1008,16 +1012,24 @@ pub fn extract_qobject(
                                     _others => original_trait_impls.push(original_impl.to_owned()),
                                 }
                             } else {
-                                let mut extracted = extract_invokables(
-                                    &original_impl.items,
-                                    cpp_namespace_prefix,
-                                    &qt_ident,
-                                )?;
-
-                                object_invokables.append(&mut extracted.invokables);
-                                object_normal_methods.append(&mut extracted.normal_methods);
+                                // Rust only methods are on the impl T block
+                                object_rust_methods.append(&mut original_impl.items);
                             }
                         }
+                        // Invokables are defined in the impl cxx_qt::QObject<T> block
+                        "cxx_qt"
+                            if path.segments.len() > 1
+                                && path.segments[1].ident.to_string().as_str() == "QObject" =>
+                        {
+                            let mut extracted = extract_invokables(
+                                &original_impl.items,
+                                cpp_namespace_prefix,
+                                &qt_ident,
+                            )?;
+
+                            object_invokables.append(&mut extracted.invokables);
+                            object_normal_methods.append(&mut extracted.normal_methods);
+                        }
                         _others => {
                             return Err(Error::new(
                                 path.span(),
@@ -1130,6 +1142,7 @@ pub fn extract_qobject(
         ident: qt_ident,
         invokables: object_invokables,
         normal_methods: object_normal_methods,
+        rust_methods: object_rust_methods,
         properties: object_properties,
         signals: object_signals,
         signal_ident,
@@ -1394,7 +1407,8 @@ mod tests {
         assert!(invokable.mutable);
 
         // Check that the normal method was also detected
-        assert_eq!(qobject.normal_methods.len(), 1);
+        assert_eq!(qobject.normal_methods.len(), 4);
+        assert_eq!(qobject.rust_methods.len(), 1);
     }
 
     #[test]
@@ -1458,7 +1472,8 @@ mod tests {
         // Check that it got the inovkables and properties
         assert_eq!(qobject.invokables.len(), 0);
         assert_eq!(qobject.properties.len(), 1);
-        assert_eq!(qobject.normal_methods.len(), 2);
+        assert_eq!(qobject.normal_methods.len(), 0);
+        assert_eq!(qobject.rust_methods.len(), 2);
 
         // Check that there is a use, enum and fn declaration
         assert_eq!(qobject.original_passthrough_decls.len(), 13);

cxx-qt-gen/src/gen_rs.rs

@@ -979,14 +979,14 @@ pub fn generate_qobject_rs(
                 .map(|ident_wrapper| invokable_generate_wrapper(i, &ident_wrapper.rust_ident))
         })
         .collect::<Result<Vec<TokenStream>, TokenStream>>()?;
-
     let invokable_methods = obj
         .invokables
         .iter()
         .map(|m| m.original_method.clone())
         .collect::<Vec<syn::ImplItemMethod>>();
-    let normal_methods = &obj.normal_methods;
 
+    let normal_methods = &obj.normal_methods;
+    let rust_methods = &obj.rust_methods;
     let original_trait_impls = &obj.original_trait_impls;
     let original_passthrough_decls = &obj.original_passthrough_decls;
 
@@ -1019,6 +1019,7 @@ pub fn generate_qobject_rs(
             #(#invokable_method_wrappers)*
             #(#invokable_methods)*
             #(#normal_methods)*
+            #(#rust_methods)*
 
             #handle_update_request
         }

cxx-qt-gen/test_inputs/invokables.rs

@@ -10,7 +10,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn invokable(&self) {
             println!("invokable");
@@ -66,8 +66,26 @@ mod my_object {
             QString::from_str("static")
         }
 
+        pub fn cpp_context_method(&self) {
+            println!("C++ context method");
+        }
+
+        pub fn cpp_context_method_mutable(&mut self) {
+            println!("mutable method");
+        }
+
+        pub fn cpp_context_method_cpp_obj(&mut self, cpp: &mut CppObj) {
+            println!("cppobj");
+        }
+
+        pub fn cpp_context_method_return_opaque(&self) -> UniquePtr<QColor> {
+            cxx_qt_lib::QColor::from_rgba(255, 0, 0, 0)
+        }
+    }
+
+    impl RustObj {
         pub fn rust_only_method(&self) {
-            println!("QML can't call this :)");
+            println!("QML or C++ can't call this :)");
         }
     }
 }

cxx-qt-gen/test_inputs/naming.rs

@@ -7,7 +7,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn invokable_name(&self) {
             println!("Bye from Rust!");

cxx-qt-gen/test_inputs/signals.rs

@@ -22,7 +22,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn invokable(&self, cpp: &mut CppObj) {
             unsafe {

cxx-qt-gen/test_inputs/types_qt_invokable.rs

@@ -23,7 +23,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn test_color(&self, _cpp: &mut CppObj, color: &QColor) -> UniquePtr<QColor> {
             color

cxx-qt-gen/test_outputs/invokables.rs

@@ -156,8 +156,24 @@ mod cxx_qt_my_object {
             QString::from_str("static")
         }
 
+        pub fn cpp_context_method(&self) {
+            println!("C++ context method");
+        }
+
+        pub fn cpp_context_method_mutable(&mut self) {
+            println!("mutable method");
+        }
+
+        pub fn cpp_context_method_cpp_obj(&mut self, cpp: &mut CppObj) {
+            println!("cppobj");
+        }
+
+        pub fn cpp_context_method_return_opaque(&self) -> UniquePtr<QColor> {
+            cxx_qt_lib::QColor::from_rgba(255, 0, 0, 0)
+        }
+
         pub fn rust_only_method(&self) {
-            println!("QML can't call this :)");
+            println!("QML or C++ can't call this :)");
         }
     }
 

cxx-qt/src/lib.rs

@@ -16,11 +16,15 @@ use cxx_qt_gen::{extract_qobject, generate_qobject_rs};
 /// #[cxx_qt::bridge]
 /// mod my_object {
 ///     #[derive(Default)]
-///     struct MyObject {
+///     struct Data {
 ///         property: i32,
 ///     }
 ///
-///     impl MyObject {
+///     #[derive(Default)]
+///     struct RustObj;
+///
+///     impl cxx_qt::QObject<RustObj> {
+///         #[invokable]
 ///         fn invokable(&self, a: i32, b: i32) -> i32 {
 ///             a + b
 ///         }
@@ -60,6 +64,38 @@ pub fn signals(_args: TokenStream, _input: TokenStream) -> TokenStream {
     unreachable!("cxx_qt::signals should not be used as a macro by itself. Instead it should be used within a cxx_qt::bridge definition")
 }
 
+/// A macro which describes that the inner methods should be implemented on the C++ QObject.
+/// This allows for defining C++ methods which are Q_INVOKABLE for QML in Rust.
+///
+/// It should not be used by itself and instead should be used inside a cxx_qt::bridge definition.
+///
+/// # Example
+///
+/// ```ignore
+/// #[cxx_qt::bridge]
+/// mod my_object {
+///     #[derive(Default)]
+///     struct Data {
+///         property: i32,
+///     }
+///
+///     #[derive(Default)]
+///     struct RustObj;
+///
+///     impl cxx_qt::QObject<RustObj> {
+///         #[invokable]
+///         fn invokable(&self, a: i32, b: i32) -> i32 {
+///             a + b
+///         }
+///     }
+/// }
+/// ```
+#[proc_macro]
+#[allow(non_snake_case)]
+pub fn QObject(_input: TokenStream) -> TokenStream {
+    unreachable!("cxx_qt::QObject should not be used as a macro by itself. Instead it should be used within a cxx_qt::bridge definition")
+}
+
 // Take the module and C++ namespace and generate the rust code
 //
 // Note that wee need a separate function here, as we need to annotate the lifetimes to allow

examples/demo_threading/src/lib.rs

@@ -214,7 +214,9 @@ mod energy_usage {
                 .ok();
             stream.flush().await.unwrap();
         }
+    }
 
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn start_server(&mut self, cpp: &mut CppObj) {
             if self.join_handles.is_some() {

examples/qml_extension_plugin/core/src/lib.rs

@@ -60,7 +60,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn increment(&self, cpp: &mut CppObj) {
             cpp.set_number(cpp.number() + 1);

examples/qml_features/src/lib.rs

@@ -40,7 +40,7 @@ mod my_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn increment_number_self(&self, cpp: &mut CppObj) {
             let value = cpp.number() + 1;

examples/qml_features/src/mock_qt_types.rs

@@ -74,7 +74,7 @@ mod mock_qt_types {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn test_signal(&self, cpp: &mut CppObj) {
             cpp.emit_queued(Signal::Ready);

examples/qml_features/src/nested.rs

@@ -14,7 +14,7 @@ mod nested {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn nested_parameter(
             &self,

examples/qml_features/src/rust_obj_invokables.rs

@@ -21,7 +21,7 @@ pub mod rust_obj_invokables {
         }
     }
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         // ANCHOR: book_cpp_obj
         #[invokable]
         pub fn invokable_mutate_cpp(&self, cpp: &mut CppObj) {
@@ -37,9 +37,10 @@ pub mod rust_obj_invokables {
         #[invokable]
         pub fn invokable_multiply(&mut self, factor: i32) -> i32 {
             self.rust_only_method(factor);
-            self.rust_only_field
         }
+    }
 
+    impl RustObj {
         fn rust_only_method(&mut self, factor: i32) {
             self.rust_only_field *= factor;
         }

examples/qml_features/src/serialisation.rs

@@ -58,7 +58,7 @@ mod serialisation {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn as_json_str(&self, cpp: &mut CppObj) -> UniquePtr<QString> {
             let data = Data::from(cpp);

examples/qml_features/src/signals.rs

@@ -43,7 +43,7 @@ pub mod signals {
     pub struct RustObj;
 
     // ANCHOR: book_rust_obj_impl
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn invokable(&self, cpp: &mut CppObj) {
             unsafe {

examples/qml_features/src/sub.rs

@@ -29,7 +29,7 @@ pub mod sub_object {
     #[derive(Default)]
     pub struct RustObj;
 
-    impl RustObj {
+    impl cxx_qt::QObject<RustObj> {
         #[invokable]
         pub fn increment_number_self(&self, cpp: &mut CppObj) {
             let value = cpp.number();